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91.
The long-term trends of total surface solar radiation(SSR),surface diffuse radiation,and surface air temperature were analyzed in this study based on updated 48-yr data from 55 observational stations in China,and then the correlation between SSR and the diurnal temperature range(DTR) was studied.The effect of total solar radiation on surface air temperature in China was investigated on the basis of the above analyses.A strong correlation between SSR and DTR was found for the period 1961-2008 in China.The highest correlation and steepest regression line slope occurred in winter,indicating that the solar radiation effect on DTR was the largest in this season.Clouds and water vapor have strong influences on both SSR and DTR,and hence on their relationship.The largest correlations between SSR and DTR occurred in wintertime in northern China,regardless of all-day(including clear days and cloudy days) or clear-day cases.Our results also showed that radiation arriving at the surface in China decreased significantly during 1961-1989(dimming period),but began to increase during 1990-2008(brightening period),in agreement with previous global studies.The reduction of total SSR offset partially the greenhouse warming during 1961-1989.However,with the increase of SSR after 1990,this offsetting effect vanished;on the contrary,it even made a contribution to the accelerated warming.Nonetheless,the greenhouse warming still played a controlling role because of the increasing of minimum and mean surface temperatures in the whole study period of 1961-2008.We estimated that the greenhouse gases alone may have caused surface temperatures to rise by 0.31-0.46℃(10 yr) 1 during 1961-2008,which is higher than previously estimated.Analysis of the corresponding changes in total solar radiation,diffuse radiation,and total cloud cover indicated that the dimming and brightening phenomena in China were likely attributable to increases in absorptive and scattering aerosols in the atmosphere,respectively.  相似文献   
92.
Using the National Center for Atmospheric Research Community Climate System Model Version 3.5, this paper examines the climatic effects of afforestation in the East China monsoon region with a focus on land–atmosphere interactions and the modulating influence of ocean variability. In response to afforestation, the local surface air temperature significantly decreases in summer and increases in winter. The summer cooling is attributed to enhanced evapotranspiration from increased tree cover. During winter, afforestation induces greater roughness and weaker winds over the adjacent coastal ocean, leading to diminished latent heat flux and increased sea-surface temperature (SST). The enhanced SST supports greater atmospheric water vapor, which is accompanied by anomalous wind, and transported into the East China monsoon region. The increase in atmospheric water vapor favors more cloud cover and precipitation, especially in the eastern afforestation region. Furthermore, the increase in atmospheric water vapor and cloud cover produce a greenhouse effect, raising the wintertime surface air temperature. By comparing simulations in which ocean temperature are either fixed or variable, we demonstrate that a significant hydrologic response in East China to afforestation only occurs if ocean temperatures are allowed to vary and the oceanic source of moisture to the continent is enhanced.  相似文献   
93.
The next generation of climate-driven, disease prediction models will most likely require a mechanistically based, dynamical framework that parameterizes key processes at a variety of locations. Over the next two decades, consensus climate predictions make it possible to produce forecasts for a number of important infectious diseases that are largely independent of the uncertainty of longer-term emissions scenarios. In particular, the role of climate in the modulation of seasonal disease transmission needs to be unravelled from the complex dynamics resulting from the interaction of transmission with herd immunity and intervention measures that depend upon previous burdens of infection. Progress is also needed to solve the mismatch between climate projections and disease projections at the scale of public health interventions. In the time horizon of seasons to years, early warning systems should benefit from current developments on multi-model ensemble climate prediction systems, particularly in areas where high skill levels of climate models coincide with regions where large epidemics take place. A better understanding of the role of climate extremes on infectious diseases is urgently needed.  相似文献   
94.
A conceptual coupled ocean-atmosphere model was used to study coupled ensemble data assimilation schemes with a focus on the role of ocean-atmosphere interaction in the assimilation. The optimal scheme was the fully coupled data assimilation scheme that employs the coupled covariance matrix and assimilates observations in both the atmosphere and ocean. The assimilation of synoptic atmospheric variability that captures the temporal fluctuation of the weather noise was found to be critical for the estimation of not only the atmospheric, but also oceanic states. The synoptic atmosphere observation was especially important in the mid-latitude system, where oceanic variability is driven by weather noise. The assimilation of synoptic atmospheric variability in the coupled model improved the atmospheric variability in the analysis and the subsequent forecasts, reducing error in the surface forcing and, in turn, in the ocean state. Atmospheric observation was able to further improve the oceanic state estimation directly through the coupled covariance between the atmosphere and ocean states. Relative to the mid-latitude system, the tropical system was influenced more by ocean-atmosphere interaction and, thus, the assimilation of oceanic observation becomes more important for the estimation of the ocean and atmosphere.  相似文献   
95.
96.
Using Scots pine ( Pinus sylvestris L.) tree-ring data, winter (September-April) precipitation variability in west central Scandinavia was reconstructed for the past five centuries. The main growth-limiting factor for pine growing in the studied area is summer temperature, but there is an additional influence of precipitation. Using principal components analysis on three tree-ring-width chronologies, a time series was yielded that contained information on winter precipitation (Pw). Using tree rings, only a small part (20%) of the interannual Pw variability could be explained. However, better agreement between the modelled and measured Pw data on semi-decadal time scales (45% variance explained) suggests that tree-ring data from the west-central part of Scandinavia contain useful information on those time scales. The driest winters, disregarding the absolute beginning of the record, were found at the beginning of the 18th century; the last half of the 20th century seems to be the wettest, at least for the past 400 years. Since our precipitation reconstruction agrees fairly well with previously published precipitation proxies, it is suggested that tree rings may add useful information to future multi-proxy reconstructions.  相似文献   
97.
中国降雪气候学特征   总被引:18,自引:1,他引:17  
刘玉莲  任国玉  于宏敏 《地理科学》2012,(10):1176-1185
利用逐日地面降雪观测资料,分析中国25oN以北范围内降雪量、降雪日数、雪带分布和各强度降雪的气候学特征,得到以下结论:①雪季长度与年降雪日数在东部呈纬向分布,大兴安岭北部最长(>210 d),长江以南最短(常年无雪或偶尔降雪);在西部青海省南部和西藏自治区北部最长(>300 d),滇、川、藏交界处及新疆自治区北部较长,南疆较短(<60 d)。年降雪量东南部最少,东北和西北北部较多(>30 mm),青海和西藏降雪量最多(>60 mm)。平均降雪强度江淮一带最大。②根据雪季降雪频次划分中国的雪带,东北大部、内蒙自治区东部、新疆北部、青藏高原大部、秦岭等地区为常年多雪带;长江以南的滇南、四川盆地、江浙沿海等地区为永久无雪带;其余地区为常年降雪带和偶尔降雪带。③不同区域各级降雪日数占总降雪日数的比例都是暴雪日数最少,大雪日数其次,小雪日数最多;但中雪降雪量占总降雪量的比例在东北北部、华北、西北、新疆、东南、青藏高原东部等区域仅高于小雪降雪量,而在黄-淮地区仅次于暴雪降雪量。④降雪年内分配在东北北部、西北、新疆、青藏高原东部等地区都呈双峰型,最多雪时节在早冬和晚冬、早春,隆冬时节并不是降雪最多时间,黄-淮和东南地区呈单峰型,东南地区峰值更陡。⑤总降雪日数和除暴雪外的各等级降雪日数与地理位置关系较明显,在中国东部主要随着纬度升高增加,在中国西部随海拔高度增加而增加;随着纬度升高,东部和西部的总降雪强度都减小,西部的小雪强度也减小。  相似文献   
98.
赵俊虎  封国林  杨杰  支蓉  王启光 《气象学报》2012,70(5):1021-1031
利用历史数据,研究了西太平洋副热带高压指数的特征,证实脊线指数和西伸脊点指数可以较好地描述西太平洋副热带高压,同时也指出这两个指数的年际和年代际变化及其不同的配置,是造成中国夏季降水时空分布和旱涝异常的复杂性、多变性的主要原因之一。据此,将西太平洋副热带高压西伸脊点指数和脊线指数的距平投影到二维平面上,对西太平洋副热带高压进行了分类,并对其各种类型下中国夏季降水进行了合成分析,发现夏季西太平洋副热带高压西伸脊点和脊线不同配置下中国夏季降水的总体分布具有明显的规律性:在西太平洋副热带高压脊线偏北的情况下,夏季降水总体表现出南北两条雨带;在西太平洋副热带高压脊线正常的情况下,夏季降水总体表现为北多南少,长江以北降水偏多;在西太平洋副热带高压脊线偏南的情况下,夏季降水总体表现为南多北少,长江流域及其以南地区降水偏多;上述3种情况下西伸脊点越偏西,降水范围越大。此外,通过计算1951—2010年各年夏季降水实况与其西太平洋副热带高压所属年份夏季降水合成的距平相关系数,发现同一类型下各年夏季降水与其合成分布总体相似,说明了西太平洋副热带高压位置对中国降水具有明显的影响,同时也说明此种分类具有一定的合理性。最后,通过对9种西太平洋副热带高压类型下北半球夏季500hPa高度场和850hPa风场距平分别进行合成,对不同西太平洋副热带高压类型下中国夏季降水的大尺度环流背景和可能机理进行了分析。  相似文献   
99.
Daily temperature records including daily minimum, maximum, and average temperature from 190 meteorological stations over China during 1951–2000 are analyzed from two perspectives: (a) long-term persistence in direction of time varies, and (b) standard deviation in direction of amplitude varies. By employing the detrended fluctuation analysis (DFA), we find all the temperature records are long-term correlated, while the exponent α obtained from DFA varies from different districts of China due to different climate conditions, such as the southwest monsoon, subtropical high, northeast cold vortex, and the Tibetan plateau, etc. After we take the standard deviation into account, a new index χ?=?α?×?σ, which has been proposed recently, can be obtained. By further rescaling it as $ \chi = \overline \chi - {{1} \left/ {5} \right.} \times {\sigma_{{\overline \chi }}} $ , we find an obvious change of χ for these three kinds of time series, from which the whole China can be divided into two groups, which are comparatively consistent with dry/wet distributions in the south–north areas over China.  相似文献   
100.
In this paper, we propose a scenario framework that could provide a scenario “thread” through the different climate research communities (climate change – vulnerability, impact, and adaptation - and mitigation) in order to support assessment of mitigation and adaptation strategies and climate impacts. The scenario framework is organized around a matrix with two main axes: radiative forcing levels and socio-economic conditions. The radiative forcing levels (and the associated climate signal) are described by the new Representative Concentration Pathways. The second axis, socio-economic developments comprises elements that affect the capacity for mitigation and adaptation, as well as the exposure to climate impacts. The proposed scenarios derived from this framework are limited in number, allow for comparison across various mitigation and adaptation levels, address a range of vulnerability characteristics, provide information across climate forcing and vulnerability states and span a full century time scale. Assessments based on the proposed scenario framework would strengthen cooperation between integrated-assessment modelers, climate modelers and vulnerability, impact and adaptation researchers, and most importantly, facilitate the development of more consistent and comparable research within and across these research communities.  相似文献   
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